
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<errno.h>
#include<unistd.h>
#include<stdio.h>
#include<string.h>
#include<stdlib.h>

extern "C"{
#include<event.h>
#include<event2/bufferevent.h>
#include<event2/buffer.h>
#include<event2/util.h>
}


int tcp_connect_server(const char* server_ip, int port);
void cmd_msg_cb(int fd, short events, void* arg);
void server_msg_cb(struct bufferevent* bev, void* arg);
void event_cb(struct bufferevent *bev, short event, void *arg);

int main(int argc, char** argv)
{
    if( argc < 3 )
    {
        printf("please input 2 parameter\n");
        return -1;
    }


    //两个参数依次是服务器端的IP地址、端口号
    int sockfd = tcp_connect_server(argv[1], atoi(argv[2]));
    if( sockfd == -1)
    {
        perror("tcp_connect error ");
        return -1;
    }

    printf("connect to server successful\n");
    struct event_base* base = event_base_new();
    struct bufferevent* bev = bufferevent_socket_new(base, sockfd,
                                                   BEV_OPT_CLOSE_ON_FREE);

    //监听终端输入事件
    struct event* ev_cmd = event_new(base, STDIN_FILENO,
                                      EV_READ | EV_PERSIST, cmd_msg_cb,
                                      (void*)bev);
    event_add(ev_cmd, NULL);

    //当socket关闭时会用到回调参数
    bufferevent_setcb(bev, server_msg_cb, NULL, event_cb, (void*)ev_cmd);
    bufferevent_enable(bev, EV_READ | EV_PERSIST);


    event_base_dispatch(base);

    printf("finished \n");
    return 0;
}

void cmd_msg_cb(int fd, short events, void* arg)
{
    char msg[1024];

    int ret = read(fd, msg, sizeof(msg));
    if( ret < 0 )
    {
        perror("read fail ");
        exit(1);
    }

    struct bufferevent* bev = (struct bufferevent*)arg;

    //把终端的消息发送给服务器端
    bufferevent_write(bev, msg, ret);
}


void server_msg_cb(struct bufferevent* bev, void* arg)
{
    char msg[1024];

    size_t len = bufferevent_read(bev, msg, sizeof(msg));
    msg[len] = '\0';

    printf("recv %s from server\n", msg);
}


void event_cb(struct bufferevent *bev, short event, void *arg)
{

    if (event & BEV_EVENT_EOF)
        printf("connection closed\n");
    else if (event & BEV_EVENT_ERROR)
        printf("some other error\n");

    //这将自动close套接字和free读写缓冲区
    bufferevent_free(bev);

    struct event *ev = (struct event*)arg;
    //因为socket已经没有，所以这个event也没有存在的必要了
    event_free(ev);
}


typedef struct sockaddr SA;
int tcp_connect_server(const char* server_ip, int port)
{
    int sockfd, status, save_errno;
    struct sockaddr_in server_addr;

    memset(&server_addr, 0, sizeof(server_addr) );

    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(port);
    status = inet_aton(server_ip, &server_addr.sin_addr);

    if( status == 0 ) //the server_ip is not valid value
    {
        errno = EINVAL;
        return -1;
    }

    sockfd = ::socket(PF_INET, SOCK_STREAM, 0);
    if( sockfd == -1 )
        return sockfd;


    status = ::connect(sockfd, (SA*)&server_addr, sizeof(server_addr) );

    if( status == -1 )
    {
        save_errno = errno;
        ::close(sockfd);
        errno = save_errno; //the close may be error
        return -1;
    }

    evutil_make_socket_nonblocking(sockfd);

    return sockfd;
}

